This application claims the priority of German Patent Document DE 101 39 527.2, filed on Aug. 10, 2001, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a fuel fractionation device for separating a low-boiling fuel fraction from a liquid fuel in an internal combustion engine comprising a fuel tank which contains the liquid fuel, a separator, to which an extracted fuel fraction mixture can be fed, a reservoir to which the fuel fraction can be fed, and a pump which extracts fuel vapor and air and has a pump drive.
A fuel fractionation device of this type is known from German Patent Document DE 199 27 177 C1 and corresponding U.S. Patent Document No. 2002062794. This fuel fractionation device has an exposed system of lines which is connected to the fuel tank and has a pump, a heat exchanger, a separator and a reservoir. The pump extracts an air/fuel fraction mixture from a gas collection space in the fuel tank via a suction line and feeds this mixture to the separator via a pressure line which includes the heat exchanger. The fuel fractionation device takes up a not inconsiderable amount of space.
The invention has as an aspect designing a fuel fractionation device of the type described in the introduction in such a manner that it requires considerably less space and, furthermore, causes less noise when it is operating.
According to certain preferred embodiments of the invention, in a fuel fractionation device of the type described in the introduction, this is achieved in that the pump and the pump drive are fixed in a housing and are accommodated removably in the fuel tank together with the separator and the reservoir, forming a structural unit.
Combining the functional elements to form a structural unit which is integrated in the fuel tank not only considerably reduces the volume of the fuel fractionation device but also reduces the structural outlay. Furthermore in the case of a fault in the structural unit, this unit can easily be removed from the fuel tank. The fact that the pump and the pump drive are accommodated in a common housing, i.e. are encapsulated, means that the noise produced is damped.
Other features are described which may be included in certain preferred embodiments of the invention.
For example, the inventive design of an annular space between the housing and the pump and the pump drive creates the possibility of accommodating further functional elements, such as an air distributor, a fuel distributor and a heat exchanger, in the housing.